https://sims4studio.com/thread/13372/creating-lods-1-2-clothing

LOD means ‘Level Of Detail’ and clothing meshes have 0-3 of them (found in the mesh section of s4studio). They are helpful for slower PCs as it optimises your content so that it can decrease its detail when the camera is at far distances.

This tutorial will show you how to make the LODs for your own clothing meshes.

If you just use your LOD0 mesh for all LODs, it’s lazy and not good for performance. The performance loss is negligible on a single piece of CC but if everybody didn’t do it then it would slow down the game majorly… so let’s learn how to make LODs!!!!!!

This mini-tutorial requires Blender, s4studio, and my LOD pack.

Next, you will want to reduce the polycount of the clothing mesh using whatever method you like. The easiest and most convenient way in Blender is to use the decimate modifier. Add it to your clothing mesh in the modifiers tab and take the bar down until you're at a comfortable polycount overall (body mesh included) for LOD1. To get an idea of an acceptable polycount you can look at similar EA meshes as a reference.

When you have hit a polycount/facecount you're happy with, apply the modifier, and then join the body mesh with the clothing mesh (ctrl + j). You may want to save before you apply the modifier so that if you ever come back to the .blend you can adjust the decimation level.

STEP 4 (optional/conditional) If there are any issues with your clothing mesh after you decimated, you should fix them now. Don't take too much time doing this because these meshes won't be seen up close (that's LOD0), so you can have some imperfections. Examples of this may be clipping with the body mesh or the UV and texture being messed up by the decimation. Most of the time you won't need to fix anything because your mesh should look fine (especially at a distance).

STEP 5Go in s4studio, and then select LOD 1 on the 'Meshes' tab. Then import your LOD1.blend and that's your LOD 1 done!!! NICE.

STEP 6 Repeat steps 2-5 for LOD2 and LOD3. It's pretty straightforward, and once you've done this process you'll know how to do it again and for future projects. Make sure for each LOD you duplicate the LOD0 .blend, and re-decimate it from scratch (if that makes sense).

All the meshes that need to be appended can be found in the LOD pack.